Arbiter Systems 1073A, Руководство по эксплуатации

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10 Physical Configuration
3.3 Cover Removal
To gain access inside the Model 1073A and change any jumper position, the instrument cover must
be removed. Remove top cover as follows:
1. Disconnect the power cord.
2. Using a T-25 driver, remove the four screws securing the cover (and rack mount ears, if used).
Lift the cover off.
3.4 Jumper Configuration
The Model 1073A has a system of jumpers and selectable shunts to configure each channel for
either AC or DC signals, and to configure the overall distribution of signals. To help identify these
features, a brief indication of each jumper’s function is given on the PC board silk-screen, near the
jumper. For reference, see Figure 3.2 on page 14.
To optimize the distribution of signals, the Model 1073A has three separate channels with four
outputs dedicated to each input channel. The configuration of each channel is virtually identical,
except for selections which determine input bussing. Input bussing is the ability to drive multiple
channels from one input. For example, the input to Channel A can drive Channel A, B and C
outputs. Channel A input can also drive Channel A and C outputs, skipping Channel B. Bussing
also allows you to use Channel B input to drive Channel B and Channel C outputs, leaving Channel
A to be independent. Otherwise, Channels A, B and C may be driven independently from their
respective inputs. See Section 3.4.2 for more information on bussing.
3.4.1 AC/DC Coupling of Inputs
To select each input channel coupling use Table 3.1 below. For bussing of additional channels from
one input channel, see Section 3.4.2 below. For either AC or DC input coupling for Channel A,
use jumpers JMP1 and JMP2. For Channel B, use jumpers JMP7 and JMP8. For Channel C use
jumpers JMP14 and JMP15. Note that Channel A consists of the group of five BNC connectors
which are rightmost when facing the rear panel. Remember to correctly set both jumpers for each
input to function properly.
Channel Both Jumpers DC Coupling AC Coupling
A JMP1, JMP2 A, A B, B
B JMP7, JMP8 A, A B, B
C JMP14, JMP15 A, A B, B
Table 3.1: Input Coupling Jumper List
AC coupling is normally used for time base signals, such as 5 or 10 MHz derived from a satellite-
controlled clock. These signals are generally square waves, or sine waves (with some limitations;
see below). DC coupling is normally used for signals such as unmodulated IRIG time codes, and
asymmetric pulse outputs such as 1PPS. DC coupling may also be used with square wave input